{"id":15058,"date":"2022-07-09T19:00:25","date_gmt":"2022-07-09T17:00:25","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=123065"},"modified":"2022-07-09T19:13:09","modified_gmt":"2022-07-09T17:13:09","slug":"how-do-i-see-noctilucent-clouds-nlcs","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/how-do-i-see-noctilucent-clouds-nlcs\/","title":{"rendered":"How do I see noctilucent clouds (NLCs)?"},"content":{"rendered":"

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By Pete Lawrence\n \t\t<\/p>

Published: Saturday, 09 July 2022 at 12:00 am<\/p>

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Night darkness is in short supply between late May and early August, as sunset is late in the day and sunrise early. In addition, the Sun\u2019<\/a>s position below the northern horizon in the middle of the night means much of the UK never sees proper darkness at all. Although this is a challenging time for stargazing, there is another phenomenon\u00a0that\u00a0can only be seen at this time of year.<\/p>\n

Noctilucent clouds (NLCs)\u00a0are ice-sheet clouds forming\u00a0at an altitude of\u00a0around 80km (50 miles) in a thin region within the mesosphere. The mesosphere is\u00a0a defined layer\u00a0of\u00a0Earth\u2019s atmosphere,\u00a0extending\u00a0from an altitude of\u00a050-120km (30-75 miles).<\/p>\n

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During the\u00a0northern\u00a0hemisphere\u2019s summer<\/a>, the temperature of the mesosphere drops and any water vapour present becomes supercooled. If small particles pass through the supercooled vapour, tiny ice crystals form creating NLCs. If you\u2019re wondering what the astronomical connection is here, the natural supply of seeding particles is the dust left after a meteor<\/a> vaporises in the atmosphere.<\/p>\n

If present, NLCs can normally be seen low above the northwest horizon between 90 and 120 minutes after sunset, or low above the northeast horizon before dawn. Extensive displays may appear low in the northwest, track through north and end low in the northeast.<\/p>\n

Despite the Sun having set for us on the ground, from the altitude of the NLC sheet the Sun is still up. Consequently,\u00a0the sheet reflects sunlight and, from our perspective at least, appears to shine at night. This is where they get their name:\u00a0noctilucent means\u00a0\u2018night shining\u2019.<\/p>\n

NLCs can be very beautiful, glowing against the deep twilight sky with a vibrant electric blue colour and often showing fine, net-like structures.<\/p>\n

Read more:<\/strong><\/p>\n